1. FIELD OF INVENTION
The present invention pertains generally to vehicular transports, and more specifically to a clamping device for forcefully retaining a snowmobile ski to the transport surface.
2. DESCRIPTION OF THE RELATED ART
Snowmobiles provide a unique source of transportation and recreation over terrain that is often times otherwise impassible. Forward skis, an endless drive belt, and relatively high power-to-weight ratios enable the snowmobile to be driven through a wide variety of winter conditions. Nevertheless, it is often quite undesirable to use the snowmobile as the sole source of transport. For both recreational and racing purposes the snowmobile is generally be carried upon a trailer, flat bed truck or similar transport to some destination point along a roadway, and then the snowmobile is unloaded and driven from that point over the terrain. At some later time, when the racing or recreational event has been concluded, the snowmobile will once again be loaded upon the transport and carried again along a roadway.
Because the snowmobile will be loaded and unloaded frequently during a snowmobiling season, the particular method used to attach the snowmobile to the transport surface is of much consequence. As will be appreciated by those who are active snowmobilers, the weather can not be counted upon for providing a comfortable and convenient environment for attaching the snowmobile to transport. In the more northerly climates, where snowmobiles find much popularity, the weather may vary from above freezing, with or without freezing rain, sleet or snow, through temperatures that are fifty or more degrees Centigrade below zero. High winds and low visibility may further hamper efforts to attach the snowmobile.
When the transport is an open type carrier such as a trailer, the transport surface will be exposed to this range of elements not only during loading and unloading, but throughout the transport. The surface will further be sprayed or coated from water and snow thrown by the pulling vehicle or other vehicles during transport. Between challenging weather conditions and exposure of the transport surface to spray, mist and dirt from the roadway, only carefully designed methods of attachment will meet with success.
One successful attachment technique is illustrated by Persau in U.S. Pat. No. 5,203,655, incorporated herein by reference. A bar extends across the snowmobile skis, and is clamped down against the transport surface. The clamping force is obtained from a bolt passing through two nuts affixed to the trailer. By rotating the bolt using a crank handle, the bolt is threaded through the nuts in the usual way. The bar is pulled by the action of the bolt threads against the nuts towards the transport surface, which in this case is a trailer. A locking hole is provided through the bar which prevents the crank from being rotated, thereby preventing theft or accidental loss of the snowmobile. The Persau device offers a relatively simple and low cost apparatus which is fully removable from the transport surface. However, the Persau device also requires a significant amount of time to install and remove. Particularly when the weather is adverse and the loading person tired from a day's ride, this method of attachment is undesirable. Furthermore, the Persau bolt must be completely removed each time the snowmobile is removed from the trailer. Upon attachment to the trailer then the bolt must be re-inserted and threaded through the nuts. While this will generally not present a problem, when the weather is unfavorable the nut threads may be exposed to ice or snow that can be very difficult to clear from the relatively small opening within the nuts. Furthermore, the repeated removal and rethreading offers much opportunity for so-called cross-threading, where the bolt threads do not accurately align with nut threads, damaging both the nut and bolt. With either severe icing or damaged threads, the Persau device may be disabled completely, preventing the snowmobile from being transported without another means for attachment.
Baker, Jr. in U.S. Pat. No. 5,044,845 illustrates another method for attachment, also incorporated herein by reference for teachings relevant to the transport of snowmobiles. A rod is used by Baker to clamp the snowmobile skis against the transport surface, and the rod is pulled against the trailer surface by a pivoting arm. By pulling upwards on a handle, the clamping mechanism is pulled downwards towards the trailer surface, Limited resilience in the trailer and clamping components allows the handle in one embodiment to be elevated over a support and rested thereon. In another embodiment, a spring provides the necessary clamping force. While the Baker device eliminates the necessity for repeated threading, several disadvantages are introduced. First and foremost, the Baker device requires substantial alteration of the transport surface. Eight slots must be cut in the surface, and clearance provided on the underside of the surface for the pivot arms. Locking of the snowmobile is not illustrated, nor is the use of the illustrated spring a reliable method of attachment which can be counted upon through time and environment. Finally, with salt and mud sprayed up from roadways, and ice and snow packing issues as well, the pivoting arm underneath the trailer will become coated relatively quickly and will therefore be prone to seizing. Fenske et al in U.S. Pat. No. 5,716,175 incorporated herein by reference illustrate a removable clamp and bar structure that requires a relatively simple ninety degree rotation at the time of placement, and then limited turning of a handle to clamp the bar down tightly. While the Fenske et al device is much improved over the prior art devices, this clamp is relatively more expensive, and still requires rotation of the clamping bolt at the time of installation, and so is subjected to the adverse affects of dirt and ice upon the relatively small threads. Furthermore, a somewhat larger slot must be provided in the trailer, and the initial tightening can be somewhat difficult, since the clamp must be held against rotation while the handle is turned. requiring a relatively coordinated two-handed installation. While this may at first appear to be of little consequence, during extreme conditions and at the end of a day's ride, seemingly simple tasks are considerably more difficult than otherwise.